Gate valve



FIG. 1 is a front elevational view of my design for a gate valve;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a right end elevational view thereof;

FIG. 4 is a left end elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

The ornamental design for a gate valve, as shown.